noun
sex ratio; gender ratio
Used in demographic, social, or statistical contexts to describe the proportion of males to females in a group.
この大学の男女比はほぼ1対1です。
The gender ratio at this university is almost 1 to 1.
出生時の男女比は自然状態で約105対100とされる。
The sex ratio at birth is said to be about 105 to 100 in natural conditions.